Accidentally Accurate: Uderzo received a mail congratulating him for his perfect depiction of the antique roadstead of Brest. Uderzo had actually drawn it without doing any research.
Author Existence Failure: Writer René Goscinny died in 1977, while Albert Uderzo was drawing the parody of Waterloo battle part of Astérix chez les Belges (Astérix in Belgium). From this point on, the rain starts (and doesn't stop until the end of the album). Uderzo continued the series as both writer and illustrator afterward.
Bad Export for You: When Optimum released Astérix and the Big Fight on DVD, Brits got the poorly received American dub of instead of the more popular British dub with BRIAN BLESSED.
The Catch Phrase Catches On: The expression "Il est tombé dedans quand il était petit." ("He fell into it [the magic potion] when he was little.") is now standard in French to designate something you got an interest to from a very young age.
No Export for You: Astérix and the Vikings was never released in the US, despite the English version being dubbed in the US with well-known actors.
There is also an Astérix album that has yet to see the light of day in English-speaking countries; Astérix et ses Amis. It's also the only post-'77 album not to be written or drawn by Uderzo; it was actually created by many other European writers and artists (except for Stuart Immonen, who's Canadian) as an 80th birthday present for Uderzo. It also has more than a few cameos from other comic book characters, which is probably why it hasn't been translated; nobody wants to deal with the headache of pleasing the various licenses.